Deletion mutation of BRAF in a serrated adenoma from a patient with familial adenomatous polyposis.

BRAF gene mutations in the colorectum have been associated with serrated adenomas and less frequently with hyperplastic polyps, villous adenomas, tubular adenomas, and carcinomas. Most BRAF mutations in the colon have been reported as a V600E substitution. We report a case with a very rare deletion mutation of BRAF (c.1799-1801delTGA, p.Val600_Lys601delinsGlu) in a serrated adenoma; the patient has familial adenomatous polyposis with a germline mutation of the APC gene (c.3578delA, p.Gln1193ArgfsX1264). Genetic studies on fundic gland polyps and tubular adenomas from the same patient failed to demonstrate BRAF mutation. This case is the first reported with a deletion mutation of BRAF found in the colon.